1. Field of the Invention
This invention relates to a system for transmitting conversation occurring within a cockpit of a commercial aircraft unbeknownst to unauthorized personnel within the aircraft, such as hijackers, directly to ground tracking stations and/or tracking aircraft and further alerting such ground tracking stations by preselecting a transponder code and/or a transmission frequency of the radio transceiver associated with the aircraft.
2. Description of the Prior Art
Voice recorder mechanisms commonly referred to as the "black box" are an integral and required instrumentation for all commercial aircraft particularly for aircraft intended for the transportation of passengers. Prior art cockpit voice or sound recorders of the type referred to is represented in the structure disclosed in U.S. Pat. No. 3,327,067 to Boniface. In the commercial aircraft industry, it is also recognized that the setting of the transponder to 7500 represents an emergency signalling that a hijacking is taking place. When such occurs, all tracking ground stations react accordingly and take appropriate action. The setting of the dual transponder control associated with aircraft instrumentation to this preselected transponder code can be done as part of the normal operating duties of the crew members and accordingly, is not readily discernible by any hijackers or unauthorized occupants within the cockpit.
However, to date the prior art does not include any transmission facility capable of being readily incorporated into the instrumentation of a commercial aircraft which allows the monitoring of the conversation of the crew members, as well as the hijackers or any occupants of the cockpit.
Based on past hijacking situations of commercial airliners, the crew members are invariably instructed to break off any communication with the ground tracking station other than specific instructions and/or information allowed by the hijackers. Accordingly, authorities on the ground frequently have a limited knowledge of the facts and circumstances surrounding the hijacking. A complete knowledge of the activities and intentions of the hijackers would of course greatly aid authorities in the proper treatment of a given hijacking or like emergency situation. This would be particularly true in situations where the conversations between the cockpit crew and the hijackers were relayed to the proper authorities without knowledge of such relay by the hijackers.
Accordingly, there is a need in the airline and commercial aircraft industry for a transmission system capable of discretely transmitting the sounds, particularly voices, emanating from within the cockpit and to transmit this audio information by means of the radio facilities associated with the aircraft or a supplementary radio transceiver facility, to ground tracking stations for the purpose of determining pertinent information concerning a given emergency situation, such as a hijacking, without knowledge of occupants of the cockpit other than the crew members. Activation of such a preferred transmission system can occur by actions of the crew members which would appear to be normal and required for the operation of the aircraft.